1. Field of the Invention
The present invention relates to an ophthalmologic apparatus which aligns an optometric unit with an eye to be examined using a joystick mechanism to inspect, observe, and image the eye.
2. Description of the Related Art
Many ophthalmologic apparatuses include a base unit having a face rest which fixes the face of an object, an inspection unit which observes/images and measures the eye to be examined, a stage unit which moves the inspection unit back and forth, left and right, and up and down relative to the base unit, and a joystick mechanism which is operated to drive the stage unit.
Many conventional ophthalmologic apparatuses use a manual stage which mechanically links the joystick mechanism to the stage unit. The joystick mechanism mechanically drives the inspection unit. The joystick mechanism allows to perform fine operation of finely driving the inspection unit back and forth and left and right and coarse operation of coarsely driving the inspection unit back and forth and left and right. This makes it possible to finely align the inspection unit with the eye to be examined or largely move the inspection unit from one eye to the other eye.
Recently, however, an increasing number of ophthalmologic apparatuses include an electric stage owing to the advantages of auto alignment and the like. The electric stage is driven by a motor or the like, and hence cannot be moved by a mechanical link such as a conventional joystick mechanism. For this reason, according to Japanese Patent Laid-Open No. 8-126611, a trackball or the like is used as a driving instruction input device for the electric stage unit. However, such device greatly differs in operational feeling from the operation of a conventional manual stage, and hence often makes the examiner feel a sense of discomfort. In addition, the trackball is spaced apart from the roller, it is difficult to simultaneously operate them with one hand, thus posing a problem in terms of operability.
In order to solve the above problem, the ophthalmologic apparatus disclosed in Japanese Patent No. 4250062 includes a detection unit for detecting the tilt angle of a joystick mechanism in place of a trackball. There is also disclosed a transmission unit for outputting the signal detected by this detection unit to a drive motor and transmitting the output of the drive motor to the inspection unit. In this case, this ophthalmologic apparatus uniformly controls the moving velocity of the optometric unit in accordance with the tilt angle of the joystick mechanism. However, since this apparatus uniformly controls the moving velocity of the optometric unit in accordance with the tilt angle of the joystick mechanism, it is impossible to perform fine operation and coarse operation which can be done by a mechanical joystick mechanism. This therefore also poses a problem in terms of operability.
In order to implement fine operation and coarse operation like those of a mechanical joystick mechanism in an ophthalmologic apparatus including an electric stage, the apparatus requires a joystick mechanism capable of performing both the operation of holding a tilt angle for fine operation and the operation of restoring a tilt angle to a neutral angle for coarse operation. This makes it possible to perform position control of the electric stage unit in fine operation, thereby allowing to perform fine alignment. In addition, it is possible to perform velocity control in coarse operation. This can quickly perform the operation of largely moving the inspection unit.
Japanese Patent Laid-Open Nos. 2006-130227 and 2008-61715 disclose ophthalmologic apparatuses each including a joystick mechanism having operation members respectively provided for fine operation and coarse operation. Operational feeling similar to that of the joystick mechanism using the manual stage is implemented by using the joystick mechanism which is provided with the operation member for maintaining a tilt angle for fine operation with frictional force and is also separately provided with the operation member for restoring to the neutral position for coarse operation.
Japanese Patent Nos. 3276682 and 4323209 disclose a joystick mechanism which switches between using frictional force for holding a tilt angle and not using frictional force. This implements a joystick mechanism which can perform both the operation of holding a tilt angle and the operation of restoring to the neutral angle.
Japanese Patent Laid-Open Nos. 2002-369799 and 2009-268682 disclose techniques of implementing fine operation and coarse operation by using the same operation member. These techniques use the joystick mechanism in a fine operation region where when the joystick mechanism is tilted within a predetermined tilt angle, frictional force is used to hold the tilt angle of the joystick mechanism, and position control is performed on the electric stage. On the other hand, the joystick member is used in a coarse operation region where when joystick mechanism is tilted to an angle larger than a predetermined tilt angle, the mechanism restores to a predetermined angle, and coarse operation control is performed on the electric stage. This implements a joystick mechanism for an electric stage which exhibits good operability with a simple arrangement.
The joystick mechanisms disclosed in Japanese Patent Laid-Open Nos. 2006-130227 and 2008-61715, however, require two operation members for fine operation and coarse operation, and hence its arrangement is complicated. In addition, the joystick mechanisms disclosed in Japanese Patent Nos. 3276682 and 4323209 require the mechanism of switching between using frictional force and not using friction force, and hence its arrangement is complicated.
The joystick mechanisms disclosed in Japanese Patent Laid-Open Nos. 2002-369799 and 2009-268682 implement fine operation and coarse operation with a simple arrangement. However, these joystick mechanisms implement tilting in an arbitrary direction throughout 360° with two rotatable shafts perpendicular to each other and has friction mechanisms provided for the respective shafts to hold the tilt in the fine operation region. For this reason, according to these mechanisms, when the operator tries to tilt the joystick mechanism toward the intermediate position of each shaft, frictional force acts from the two shafts, resulting in uneven operational feeling. With such uneven operational feeling, it is difficult for the examiner to operate the joystick mechanism in a desired aligning direction. This may lead to a deterioration in alignment accuracy or a decrease in throughput.
The joystick mechanism disclosed in Japanese Patent No. 4323209 generates frictional force on a spherical moving member which moves synchronously with the tilting of the joystick mechanism, and hence can obtain operational feeling independently of the tilting direction. However, the arrangement of this mechanism is complicated, as described above.
In consideration of the above problems, the present invention provides an ophthalmologic apparatus including a joystick mechanism which can obtain uniform operational feeling with a simple arrangement.